Answer
$5\;g$.
Work Step by Step
The given values are
Base $B=500\;mL$.
Rate $R=1$.
Let the pure powdered sodium bicarbonate is $P=x$
The formula is
$\Rightarrow \frac{P}{B}=\frac{R}{100}$
Substitute all the values.
$\Rightarrow \frac{x}{500\;mL}=\frac{1}{100}$
Cross multiply.
$\Rightarrow 100x=500\;mL$
Divide both sides by $100$.
$\Rightarrow x=5\;mL$.
Convert $mL$ to $g$.
$\Rightarrow x=5\;mL\times \frac{1g}{1mL}$.
Simplify.
$\Rightarrow x=5\;g$.
